#include <stdio.h>
int main()
{

    const int fx[] = {0, -2, -1, 1, 2, 2, 1, -1, -2};
    const int fy[] = {0, 1, 2, 2, 1, -1, -2, -2, -1};
    short int posh[2], size[2];

    scanf("%hd %hd %hd %hd", size, size + 1, posh, posh + 1);
    _Bool allp[40][40] = {0};
    long long int f[40][40];

    for (int i = 0; i < 9; i++)
    {
        allp[fx[i] + posh[0]][fy[i] + posh[1]] = 1;
    }
    for (int i = 0; i <= size[0]; i++)
    {
        for (int j = 0; j <= size[1]; j++)
        {
            if(i+j==1){
                f[i][j]=1;
            }else{
                f[i][j] = f[i - 1][j] + f[i][j - 1];
            }
            if (allp[i][j] == 1)

                f[i][j] = 0;
        }
    }
    printf("%lld", f[size[0]][size[1]]);
    /* for (int i = 0; i < size[0]; i++)
    {
        for (int j = 0; j < size[1]; j++)
        {
            printf("%d", allp[i][j]);
        }
        printf("\n");
    } */
}
